creatinine test

What is a creatinine test?


This test evaluates the levels of creatinine in the blood and/or urine. Your muscles produce creatinine as a waste product during routine, everyday action. In a typical state, your kidneys remove creatinine from your blood and excrete it in urine. Creatinine can accumulate in the blood and be discharged less urine if there is a renal issue. Unusual amounts of creatinine in the blood or urine may indicate renal disease.


What does it serve?


To determine whether your kidneys are functioning correctly, a creatinine test is utilized. It is frequently requested in conjunction with blood urea nitrogen (BUN), a kidney test, or as part of a full metabolic panel (CMP). A CMP is a collection of examinations that offer data about various bodily organs and systems. A normal checkup typically includes a CMP.

Is a creatinine test necessary and why?

If you have kidney disease symptoms, you could require this test. These consist of:


  • Fatigue
  • rounding of the eyes, puffiness
  • swelling in your ankles or feet
  • a diminished appetite
  • frequent, uncomfortable urination
  • the foaming or bloody urine


If you have specific kidney disease risk factors, you could also require this test. Kidney illness may put you at greater risk if you have:


  • Diabetes type 1 or type 2
  • elevated blood pressure
  • a history of renal illness in the family


How does a creatinine test work?

Blood or urine samples can be checked for creatinine


For a blood test for creatinine:

A tiny needle will be used by a medical practitioner to draw blood from a vein in your arm. A tiny amount of blood will be collected into a test tube or vial once the needle has been placed. The needle may hurt somewhat when it enters or exits your body. Normally, this takes within five minutes.

or a urine creatinine test:


You’ll be asked to collect all of your urine over the course of a 24-hour period by your doctor. You will get a container for collecting your urine as well as instructions on how to gather and keep your samples from your doctor or a laboratory expert. The following procedures are often performed on a 24-hour urine sample:


  • In the morning, empty your bladder and flush the pee. Keep a time log.
  • Save all of your passed pee for the following 24 hours in the container supplied.
  • Your urine receptacle should be kept in a cooler with ice or the refrigerator.
  • As directed, return the sample vial to the lab or the office of your healthcare practitioner.

. Will there be anything I need to do to get ready for the test?


Before your test, you could be instructed to abstain from cooked meat for 24 hours. Cooked beef can momentarily increase creatinine levels, according to studies.

Does the test include any risks?


The danger of getting a blood test is quite low. Even though you can have some little discomfort or bruising where the needle was inserted, most side effects are transient.


Taking a pee test carries no danger.


How you get ready

Creatinine levels in your blood are determined via a routine blood test (serum creatinine). In order to prepare for the test, your doctor could advise fasting the night prior.


You might need to collect urine over the course of 24 hours in containers the clinic will give for the creatinine urine test.


You might have to refrain from eating meat for a particular amount of time before either test. You should probably cease using a creatine supplement.

What do the findings indicate?


In general, renal disease or any disorder that impairs kidney function is indicated by high levels of creatinine in the blood and low amounts in the urine. These consist of:


  • autoimmune conditions
  • infection of the kidneys with bacteria
  • bladder obstruction
  • heart attack
  • Consequences of diabetes


Atypical findings, however, don’t usually indicate renal disease. Temporarily rising creatinine levels can be caused by the following conditions:


Obstetrics Vigorous exercise


consuming a lot of red meat


certain medications. The negative effects of several medications cause elevated creatinine levels.

Speak with your healthcare professional if you have any queries regarding your results.


Study up on laboratory procedures, reference intervals, and reading findings.


Do I need to know anything more about a creatinine test?


A creatinine clearance test may also be requested by your doctor. In a creatinine clearance test, the amount of creatinine in blood and urine are contrasted. Compared to a blood or urine test alone, a creatinine clearance test may give more reliable results on kidney function.


Can my doctor tell if my kidneys are healthy by looking at the level of creatinine in my blood?


No. The best approach to assess the health of your kidneys is not to look at the level of creatinine in your blood. This is so because your age, race, gender, and physical size all have an impact on the amount of creatinine in your blood. (In other words, these variables determine what is seen as “normal”.) Looking at your glomerular filtration rate is the greatest approach to determine if your kidneys are functioning properly (GFR).


On your blood test record, you may see the GFR, a common laboratory test. Your creatinine level is calculated along with your age, gender, race, and weight to determine your GFR. Your healthcare professional can determine if you have renal disease using your GFR value. Your GFR may indicate renal disease if it is:


three months of being under 60

over 60 with kidney damage symptoms (having protein in the urine is a sign of kidney damage)


Do I require any further tests?


Yes, a urine test is a crucial additional test to determine kidney function. You’ll be asked to urinate into a specimen cup, which is a clean cup. The test just requires two teaspoons or so of urine. The urine sample will be submitted to a lab for an ACR (albumin-to-creatinine ratio) test. If you have albumin, a kind of protein, in your urine, an ACR will reveal this. Less than 30 mg/g of albumin is considered normal in urine. Even if your GFR is higher than 60, anything above 30 mg/g may indicate you have renal disease.


The likelihood that a person’s renal illness would worsen is also assessed using this test. The danger of advancement is what this is. High levels of albumin indicate a higher risk.


Is it ever possible to assess renal function only based on creatinine?


This is a significant query. There is a distinction between measuring your serum creatinine (also known as “creatinine”) and your creatinine clearance (also known as “creatinine clearance”). The two lab tests here are distinct. Creatinine clearance is not included in a regular lab report, although serum creatinine is.


Urine must be timed in order to measure creatinine clearance. Your whole 24-hour urine output is stored (collected) in a container, and the contents are then examined. The outcome reveals how much creatinine has entered your urine after passing through your kidneys. It demonstrates how well your kidneys are eliminating waste from your blood.


clearance of creatinine


The ability of the kidneys to remove creatinine from the circulation for excretion in urine is measured by creatinine clearance.


Creatinine levels in 24-hour urine samples and serum samples obtained over the same time period are often used to calculate creatinine clearance. However, shorter times may be employed for urine samples. It’s crucial to collect the urine sample at the proper time.


Milliliters of creatinine per minute per body surface area (mL/min/BSA) is the unit used to measure creatinine clearance. Men aged 19 to 75 often fall between the range of 77 to 160 mL/min/BSA.

The usual range for creatinine clearance in females, according to age, is as follows:


78 to 161 mL/min/BSA for ages 18 to 29, 72 to 154 mL/min/BSA for ages 30 to 39, 67 to 146 mL/min/BSA for ages 40 to 49, and 62 to 139 mL/min/BSA for ages 60 to 72.

For elderly persons, there are no established standards.


Results that are below the range expected for people your age may indicate impaired kidney function or diseases that reduce blood flow to the kidneys.

Creatinine to albumin ratio

The albumin/creatinine ratio is a different way to evaluate the urine creatinine count. Blood contains the protein albumin. There should be little to no albumin in the urine since healthy kidneys often do not filter it out of the blood.


The albumin/creatinine ratio quantifies the ratio of albumin to creatinine in a urine sample. The data are presented as the ratio of albumin in milligrammes (mg) to creatinine in grammes (g). The following outcomes show a healthy kidney:


Less than 17 mg/g for adult males

Less than 25 mg/g for adult women

A higher-than-average result might indicate renal illness. The outcome may specifically point to a diabetes complication known as diabetic nephropathy, or diabetic kidney disease.


The findings of a creatinine test will be discussed with you by your doctor or another healthcare professional, who will also explain what the information implies for a diagnosis or course of treatment.

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